After an upgrade or change in the site's theme, the font size in the black-bar administration menu at the top of the screen will revert back to 9-pt font size, which is difficult to read.  You can override the font size by adding this line to your stylesheet in your theme:   body #admin-menu { font-size: 10px; }

1. Use an FTP or the Cpanel File Manager to navigate to  "drupal folder > sites >all >themes > THEMENAME > style.css
2. Select the file style.css
3. Make a backup copy of style.css before doing any editing.

4. Open style.css for editing

5. Paste the text body #admin-menu { font-size: 11px; } into the body. Make sure it's not in between any { }.

6. Save the file.

7. Back at your site, flush the cached administration menu by using the link in the top left hand corner of the Black Admin Bar. It is reached by Home > Flush all caches > Administration Menu